2. Prior Art
The extractive mining is the science of extracting the metals or other products with metallic content from the mines. In other words, it is the way in which the mineral is retrieved from the ore deposit, treated inside the mine and how is transported to the plant.
According to the exploitation method, there are 2 types. The first one called open pit exploitation which is a set of operations needed to extract the rock or the mineral with economic value, through the retrieval of the mineral recovering in a partial or complete way from the surface. This type of exploitation is used when the mineralized body is over or near the surface.
The second method is called underground exploitation. Access tunnels are built to reach the mineralized belt. The rock retrieval is performed through the use of explosives. The mineral is removed taking advantage of the weight of the mineral itself. In general this type of exploitation could be separated into three groups:                Rooms and pillars: the mineral is removed and empty rooms are being generated inside the hill, where mining pillars are installed. Once the mineral is treated the room is filled with sterile material to avoid the hill from collapsing.        Block caving: This method consists of preparing a block through different levels. The block is weakened on its base by digging tunnels through it so it is solely supported by the pillars being formed in different rooms.        Sub Level Caving: This is a high cost method based on the principle described above, in which parallel production rooms are prepared every 11 meters in the horizontal and 11 meters in the vertical so as to cover the mineralized body to be exploited.        
The mineral is extracted with a very uneven shape from the mine, and its reduction is needed for evenness. This is carried out in different stages such as crushing and grinding depending on the reduction size required.
During the crushing process the size reduction of the mine layers is produced to the required size according to the hydrometallurgical point to be used. Generally, there are three crushing stages are passed where the mineral is reduced to 4″ to 8″ and finally ¼″ a ⅜″ to be sent to the fine heap pile.
The grinding process is one of the simplest current method for mineral comminution and with other supplementary stages to obtain in a selective and pure way the copper product. This stage is intended to reduce the size of the incoming mineral to produce fines leaving it under certain conditions for a new process. This operation could be carried out under dry or wet conditions.
Nevertheless, during the grinding and crushing processes, elements which are dragged by the material are detected on the conveyor belts. Such elements usually are sticks or wood residues, which were used in underground exploitation.
At present, the task of removing such sticks from the conveyor belts is carried out manually and/or mechanically which has some disadvantages such as:                Decrease in productivity due to the fact that the conveyor belt is stopped during the removal of the foreign elements.        Costs associated to the personnel involving the manual and/or mechanical removal.        The manual removal of the sticks from the conveyor belt is an activity which has a high accident rate risk.        The operators in charge of the manual reposition are subjected to a constant physical demand in harsh environmental conditions.        